Workflow `train-bw28b` on sp20-aux-h-fixed @ 71eab9a25 terminated at
epoch=1 end after 56m wall-clock per
`feedback_kill_runs_on_anomaly_quickly`.
Epoch 1: 490399 trades, 246196 wins, 244203 losses, PF=0.946 — WR =
50.20% (vs Phase 1 = 50.21%, Δ = -0.01pp). Squarely in the runbook's
pre-declared falsification band.
Mechanistic finding (stronger than just "WR didn't move"): the
action distribution is essentially bit-identical across Phase 1
([0,1] / sentinel 0.5) and Phase 2 ([-1,+1] / sentinel 0.0)
encodings — drift < 0.5% on every action bin (run-to-run noise
floor). The policy made the SAME action choices regardless of slot
121's encoding. State[121] has zero behavioral effect on action
selection in either encoding. `pred_tanh = 0.66` in both phases
confirms the aux head IS producing strongly directional predictions
and the bridge IS conducting them — the policy is just ignoring
them entirely.
Hypothesis refinement (vs Phase 2 spec's "encoder can't extract
directional alpha in 3 epochs"): the encoder's weights for state[121]
are effectively zero. This dim was added by H6 with only 3 epochs of
training, while the first 121 dims have had thousands of training
steps to develop meaningful weights. Slot 121's gradient leverage is
dwarfed by the trained dims regardless of input magnitude. This is a
new-dim cold-start weight-init problem, not an encoding problem.
Implication: amplitude scaling (Phase 2 spec's fallback suggestion)
won't help — encoder weights are already near-zero, gradient
propagation through them stays near-zero regardless of input scale.
The deeper fix routes aux signal through a path that BYPASSES the
cold-encoder problem.
Phase 2 wiring stays merged per `feedback_no_functionality_removal`:
the recentered encoding is the better choice on principle (matches
`pearl_first_observation_bootstrap`) even when the bridge isn't
producing measurable WR effect.
Pivot to H6 Phase 3 (combined per
`pearl_no_deferrals_for_complementary_fixes`):
- (α) Bypass-head: small linear head `aux_dir_prob → Q_dir_bias`
summed into Q_dir output post-encoder (parallel skip connection).
- (β) Aux→Q-target shaping: inject aux conviction into the Bellman
target at trade-close events. Event-driven per
`pearl_event_driven_reward_density_alignment`; bypasses the
encoder entirely via the training-signal path.
Distinct mechanisms, non-overlapping refactor scopes — pearl
prescribes one atomic plan.
Refs
────
- docs/plans/2026-05-12-sp22-h6-phase2-recenter.md (Phase 2 spec)
- pearl_first_observation_bootstrap (Phase 2 encoding rationale)
- pearl_event_driven_reward_density_alignment (β motivation)
- pearl_no_deferrals_for_complementary_fixes (combined plan)
- feedback_no_functionality_removal (keep Phase 2 wiring merged)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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